The invention relates to a gripping device for a component mounting machine, said gripping device comprising a gripping device body with a finger portion, said finger portion being provided with at least two elongate fingers made in one piece, each finger having an outer edge, said outer edges being provided for, in cooperation, gripping a component, said at least two fingers being flexible in relation to each other so that the outer edges of the fingers are movable towards and away from each other.
NO-B-167 366 shows a gripping device of this type in which two gripping fingers made in one piece extend parallel with each other. One of the fingers has a portion with two thin, parallel walls thereby making it elastically deformable. When a lateral pressure is applied directly on the finger, it is moved towards the other finger.
DE-A1-196 44 502 shows a gripping device comprising fingers which are made integrally with the body of the gripper. Each finger is connected to the body of the gripping device via a narrow bridge forming a relatively rigid hinge. The inner end of each finger is provided with a lever and a disc is arranged for pressing the levers thereby causing the fingers to tilt about their relatively rigid hinges.
U.S. Pat. No. 5,458,388 shows a gripping device comprising a vacuum chamber provided with a piston that is retracted when a vacuum is applied. The piston presses on levers connected to gripping fingers which are moved towards each other by tilting about hinge portions of the fingers.
The above-mentioned devices are characterised in that the gripping fingers are made in one piece and that a force is applied for forcing the fingers towards each other. The fingers are deformed elastically and the inherent elasticity of the finger material causes the fingers to be moved away from each other once the applied force is removed again.
When gripping and mounting very small components, there is a need for accurately controlling the fingers that grip the components. The known gripping devices may be accurate in their gripping action, but when the components are to be released by removal of the applied force that forces the fingers towards each other, the movement of the fingers are totally dependent on the inherent elasticity of the finger material. This mayxe2x80x94especially over timexe2x80x94cause inaccurate and unforseeable positions of the fingers which is most undesirable in precision machine works.
The object of the invention is to provide a gripper that overcomes this problem.
This is achieved by arranging the gripper device so that movement of at least one finger is controlled by a slide engaging a part of the finger portion remote from said finger for positive movement of said finger in different directions, said slide being displaceably mounted on the gripping device body.
The term xe2x80x9cpositive movementxe2x80x9d when used in this specification is meant to mean movement in either direction directly and unambiguously controlled by a positive engagement between the slide and the finger portion.
Thereby, the movements of the gripper fingers are controlled and forseeable at all times during the gripping and releasing procedures.
Preferably, the finger portion is made in one piece with the gripping device body thereby reducing the number of separate parts in the gripping device. This facilitates assembling of the gripping device and furthermore eliminates any play and requirements to manufacturing tolerances between the otherwise two parts.
In a preferred embodiment the slide is provided with a notch that cooperates with a guiding knob provided on the finger portion. When the slide is displaced, the guiding knob is displaced accordingly causing the fingers of the finger portion to be displaced towards or away from each other.
Preferably, the finger portion is provided with two fingers, one of said fingers being in substantially rigid relation to the gripping device body, the other being flexible in relation to the gripping device body. The flexibility may be achieved by providing a narrow tongue interconnecting the two fingers, and in a preferred embodiment the tongue extends substantially parallel with a longitudinal direction of the fingers and is connected to one finger at a first end thereof and to the other finger at a second end thereof. This structure results in a slim design of the finger portion, while maintaining its high flexibility. It is therefore especially suitable for mounting of small components even in narrow places.
A pneumatic actuator may be provided for displacing the slide in relation to the gripping device body thereby making it suitable for any kind of mounting machine where compressed air is available. However, other types of actuators may be applied, e.g. electric motors.
In order to control the movement of the slide a guideway may be provided in the slide, said guideway being able to cooperate with a guiding pin provided on the gripping device body.